A 10 kg box is resting on a smooth (frictionless) horizontal surface of a table. You pull the box by the attached ribbon with a force of 40 N at a 30 degrees angle from the surface of the table. Find the acceleration of the box and the magnitude of the
normal force. Assume that friction can be neglected.

Draw a free-body diagram and identify all forces.

Find the sum of all forces in the horizontal (x) and vertical (y) direction and use Newton's 2nd law:

ā F

_{x}= 40N cos(30) = ma, a=40N cos(30)/10 kg = 3.5 m/sĀ²ā F

_{y}= 40N sin(30) +F_{n}-mg=0, F_{n}=mg - 40N sin(30) = 10(9.8) N - 20 N= 78 N